A Turning Point for Nuclear Deterrence in Europe

Examining the implications of the U.S. role in NATO and evolving conversations on nuclear deterrence post-Trump era.

Surya

•February 5, 2026•5 mins read

Europe reassesses NATO and nuclear deterrence as trust in U.S. erodes

Not Started

1. NATO Rupture and Crisis of Strategic Trust

The recent confrontation between Europe and the United States over Greenland has exposed a deeper rupture within the North Atlantic Treaty Organization (NATO). While the immediate dispute may be diplomatically managed, Europe’s trust in the U.S. as a reliable security guarantor has been fundamentally shaken.

NATO was established in 1949 as a collective defence alliance against the Soviet Union, with the U.S. as the principal guarantor of European security. Its credibility has rested less on formal treaties and more on political trust and shared threat perceptions.

The U.S. President’s coercive posture towards Denmark, a NATO member, has disrupted this foundation. When the hegemon questions the sovereignty of an ally, the alliance’s deterrent credibility is weakened.

If this erosion of trust is ignored, NATO risks becoming a hollow institutional shell, particularly as a nuclear alliance where assurance and predictability are essential.

Alliance credibility depends on trust, not just capability; without trust, deterrence collapses into uncertainty.

2. Europe’s Security Dilemma After the U.S. Reversal

Europe now faces a strategic dilemma: whether to continue relying on a U.S.-centric security architecture or to develop an autonomous framework. This debate is occurring as the last remaining bilateral nuclear arms control treaty between the U.S. and Russia expires.

The end of the New START Treaty on February 5 removes a key constraint on U.S. and Russian nuclear arsenals, intensifying European anxieties. Security planning is thus acquiring urgency and sharper political overtones.

Europe’s response will shape not only continental defence but also the future orientation of nuclear deterrence thinking. Choices made now will determine whether nuclear weapons remain central or become one element within a broader security framework.

Structural dependence without political reliability creates strategic vulnerability; failure to adapt invites insecurity.

3. Persistence and Limits of Nuclear Deterrence Thinking

Since the Nuclear Non-Proliferation Treaty (NPT) institutionalised nuclear inequality, deterrence theory has remained remarkably static. Nuclear weapons continue to be portrayed as the ultimate guarantor of peace despite changing threat landscapes.

Over time, global security threats have shifted towards terrorism, climate change, economic stress, inequality, and regional conflicts. These challenges are largely immune to nuclear solutions, yet nuclear possession remains privileged in strategic discourse.

This persistence reflects intellectual inertia rather than empirical validation. If unexamined, it risks misallocating resources and attention away from more relevant security tools.

Outdated deterrence logic can obscure contemporary security realities and policy priorities.

4. Certainty vs Uncertainty in Nuclear Deterrence

Early nuclear debates revolved around whether deterrence required certainty of retaliation or merely uncertainty. Some states relied on ambiguity to deter adversaries, allowing doubt rather than assurance to shape behaviour.

India–Pakistan relations between the 1980s and 1998 and Israel’s opaque nuclear posture exemplify deterrence through uncertainty. In contrast, Cold War superpowers emphasised certainty through testing and stockpiling.

Despite doctrinal differences, a powerful taboo against nuclear use emerged. No nuclear weapon has been used since 1945, even as tactical and “usable” nuclear weapons were developed.

Deterrence has worked as much through restraint and taboo as through arsenals; ignoring this distorts strategic lessons.

5. Arms Control, Modernisation, and a Return to Cold War Logics

Arms control agreements and non-proliferation norms have contributed to the long absence of nuclear use. However, contemporary trends suggest a reversal of restraint.

Major powers are modernising and expanding their arsenals:

China has reportedly added ~100 warheads annually since 2023, reaching 600
The U.K. reversed its drawdown policy and now holds 225 warheads
Current stockpiles:
- U.S.: 5,459
- Russia: 5,277

If these numbers begin to rise post–New START, it would signal a return to Cold War deterrence assumptions.

Renewed arms racing undermines decades of normative restraint and increases systemic risk.

6. Lessons from the Ukraine War

The war in Ukraine challenges conventional nuclear deterrence assumptions. Russia issued nuclear threats before and during the conflict, yet these were countered not by nuclear escalation but by credible conventional and political responses.

Ukraine, a non-nuclear state, has resisted a nuclear-armed adversary with external support, despite territorial losses. This demonstrates that nuclear weapons do not automatically translate into decisive coercive advantage.

The response to Russian threats relied on ambiguity regarding nuclear retaliation combined with certainty of strong non-nuclear consequences.

Credible defence and collective response can deter nuclear coercion without nuclear use.

7. Europe’s Emerging Security Architecture Choices

Europe is now debating alternatives to U.S.-led security guarantees. Proposals range from extending the French and British nuclear umbrella to building a broader defensive alliance with limited nuclear elements.

An ad hoc Coalition of the Willing, largely European, has already emerged to support Ukraine’s security. This reflects experimentation with non-U.S.-centric defence arrangements.

The strategic choice ahead is whether Europe constructs a replacement nuclear alliance or a defence framework where nuclear weapons are subordinate rather than central.

Security architecture design will shape future norms around nuclear weapons and deterrence.

Conclusion

The rupture within NATO has reopened fundamental questions about trust, deterrence, and the role of nuclear weapons in contemporary security. As Europe reassesses its dependence on the U.S., it has an opportunity to rethink deterrence beyond Cold War paradigms. Whether this moment leads to renewed nuclear centrality or a more diversified security approach will influence global nuclear discourse and stability for decades to come.

Quick Q&A

Everything you need to know

The rupture between Europe and the United States highlights a fundamental shift in NATO from a trust-based alliance to a more transactional and uncertain security arrangement. NATO was founded in 1949 as a collective defence pact where the credibility of U.S. nuclear and conventional guarantees was central to European security. The U.S. acted as primus inter pares, and trust—rather than formal legal obligation alone—was the glue that bound the alliance together. The Greenland episode under President Trump has shaken this foundation by signalling that U.S. strategic commitments can be subordinated to unilateral political and economic interests.

This erosion of trust matters deeply in a nuclear alliance. Nuclear deterrence relies not only on weapons and doctrines but also on the belief that an ally will act when required. If European states begin to doubt the U.S. willingness to uphold Article 5 commitments, NATO’s deterrent value weakens even if its military capabilities remain intact. The article correctly notes that without trust, NATO as a nuclear alliance is effectively hollowed out.

Historically, alliances such as NATO have survived crises—from Suez to Iraq—but the present rupture is qualitatively different because it questions the reliability of the hegemon itself. For UPSC interviews, this development can be analysed as part of a broader trend of weakening multilateralism and the emergence of a more fragmented, interest-driven global security order.

The expiration of the New START treaty marks a critical inflection point for global nuclear stability. New START was the last remaining bilateral arms control agreement limiting the strategic nuclear arsenals of the U.S. and Russia. Its existence not only capped warhead numbers but also provided transparency and predictability through verification mechanisms. With its expiry, the global nuclear order risks sliding back toward Cold War-style arms racing.

For Europe, this development is particularly destabilising. Europe’s security has historically rested on extended deterrence backed by U.S.–Russia arms control arrangements. If both powers begin expanding their stockpiles from already massive levels, Europe becomes a more exposed theatre of great-power rivalry. This is compounded by the erosion of trust in the U.S. as a reliable security guarantor, forcing European states to reconsider their strategic assumptions.

The broader implication is normative. Arms control agreements reinforced the global nuclear taboo by signalling restraint among major powers. Their collapse sends a message that nuclear weapons are once again central to power politics. For UPSC aspirants, New START’s expiry illustrates how arms control is not merely technical diplomacy but a cornerstone of international security architecture.

Nuclear deterrence thinking has evolved in practice but remains conceptually stagnant. In the early nuclear era, debates centred on whether deterrence depended on certainty or uncertainty of retaliation. Some states relied on ambiguity—such as Israel’s opaque nuclear posture—while others, particularly during the Cold War, emphasised certainty through large arsenals and demonstrative testing. Over time, however, a strong taboo against nuclear use emerged, reinforced by the fact that no nuclear weapon has been used since 1945.

Despite this, doctrinal thinking still treats nuclear weapons as the ultimate guarantor of security. This is increasingly disconnected from contemporary threats such as terrorism, climate change, economic instability, and cyber warfare—none of which can be meaningfully addressed through nuclear means. Yet, great-power rivalry has revived old deterrence frameworks without adequately integrating lessons from decades of nuclear non-use.

The Ukraine war underscores this disconnect. Russia issued nuclear threats, but deterrence operated through the certainty of a strong conventional response with ambiguous nuclear signalling. For UPSC interviews, this illustrates why deterrence theory needs updating to reflect behavioural evidence rather than Cold War abstractions.

The Ukraine war offers a powerful real-world test of nuclear deterrence assumptions. Russia, a major nuclear power, repeatedly invoked nuclear threats before and during the conflict. Yet these threats did not translate into nuclear use, nor did they decisively deter Ukraine or its supporters. Instead, deterrence functioned through credible conventional retaliation, economic sanctions, and political isolation, while keeping nuclear escalation deliberately ambiguous.

Ukraine’s experience demonstrates that a non-nuclear state can resist a nuclear-armed adversary, provided it has strong domestic resolve, external support, and effective conventional capabilities. Although Ukraine has suffered territorial losses, it has not been defeated, challenging the notion that nuclear weapons automatically confer decisive strategic advantage.

For policymakers, this case suggests that security can be built through layered deterrence combining conventional strength, alliances, and economic tools. In UPSC interviews, Ukraine can be cited to argue that nuclear weapons are neither necessary nor sufficient for national defence in all contexts.

Europe faces a strategic choice that will shape the future of nuclear deterrence. One option is to seek a replacement nuclear umbrella, potentially centred on France and the U.K. This could enhance strategic autonomy but risks proliferation pressures, duplication of capabilities, and internal political resistance within Europe. It may also reinforce outdated notions of nuclear primacy.

An alternative path is building a defensive alliance where nuclear weapons play a limited, background role. Initiatives like the Coalition of the Willing supporting Ukraine suggest a model based on conventional deterrence, collective resilience, and political solidarity. This approach aligns better with contemporary security challenges and lessons from Ukraine.

The choice Europe makes will influence global nuclear discourse. A shift away from nuclear-centric security could strengthen the nuclear taboo and encourage arms control revival. For UPSC aspirants, this debate highlights how regional security choices can reshape global strategic norms.